//
// Created by wze-zero on 2024/10/20.
//
#include <iostream>
#include <iomanip>

using namespace std;

double max3(int num1, int num2, int num3) {
    if (num1 > num2 && num1 > num3) {
        return num1;
    } else if (num2 > num1 && num2 > num3) {
        return num2;
    } else {
        return num3;
    }
}

int main() {
    int num1, num2, num3;
    double num;
    cin >> num1 >> num2 >> num3;
    num = max3(num1 + num2, num2, num3) / (max3(num1, num2 + num3, num3) + max3(num1, num2, num2 + num3));
    cout << fixed << setprecision(2) << num << endl;
    return 0;
}